The present invention relates to apparatuses and methods for treating a substrate. More specifically, the present invention is directed to apparatus and method for drying a substrate using supercritical fluid.
Conventionally, a substrate wet-treated with chemicals and deionized water (DI water) is dried by supplying a mixed gas of isopropyl alcohol (IPA) and nitrogen (N2). However, it is difficult to drain DI water supplied to fine patterns formed at a substrate during a substrate drying treatment. Also it is difficult to cope with dry conditions suitable for the kind of materials for the fine patterns. Accordingly, dry treating methods using supercritical fluid have been adopted to effectively dry wet-treated fine patterns.
An example of the dry treating methods using supercritical fluid is disclosed in Japanese Patent Publication No. 08-250464. According to the above-mentioned patent, a dry treating method includes carrying a substrate into a high-pressure container that is a supercritical treating apparatus, performing a series of wet treatments, and introducing liquid carbon dioxide into the high-pressure container to be substituted with alcohol on the surface of the substrate and to raise a temperature. Thus, a state of the carbon dioxide is converted to a supercritical state to perform a supercritical dry treatment and then decompression is conducted.
Unfortunately, the foregoing method encounters stability-related problems such as corrosion caused by treating chemicals because the treating chemicals should be introduced into a high-pressure container. In addition, since a treating apparatus should be durable against high pressure, large-diameter pipes are substantially unusable. For this reason, time required for supplying and draining the treating chemicals is long enough to lower production. Moreover, it is wasteful and impractical to perform a wet treatment (not requiring a high pressure) in the high-pressure container.